An apparatus for inflating an air bag is disclosed in U.S. Pat. No. 5,100,174. The apparatus disclosed in the '174 patent includes an inflator which generates gas for inflating the air bag. The inflator and the air bag are contained in a module which is mounted on a vehicle steering wheel.
The inflator in the apparatus disclosed in the '174 patent contains a body of gas generating material which, when ignited, produces the gas for inflating the air bag. The inflator also contains an igniter which is actuated upon the occurrence of vehicle deceleration indicative of a collision. The igniter includes an ignition charge and an output charge. When the vehicle experiences deceleration indicative of a collision, the ignition charge is ignited electrically. The ignition charge then produces combustion products which ignite the output charge. The output charge, in turn, produces combustion products which emerge from the igniter to ignite the body of gas generating material in the inflator. A large volume of gas is rapidly generated as a product of combustion of the gas generating material. The gas flows through a plurality of filters in the inflator and outward from the inflator to the air bag for inflation of the air bag.